Photographic film developing and fixing apparatus



y 8, 1951 J. P. MITCHELL 2,551,892

PHOTOGRAPHIC FILM DEVELOPING AND FIXING APPARATUS Filed Aug. 2, 1948 2 Sheets-Sheet 1 24 3 /7 33 2a 27 kg r H l 1 5 M /5 33 Z6 Z5 4/ Z5 v 2/ Z6 9 -22 Z Z/ 30 J'J/Z Jam 1? MITCHELL INVENTOR.

BY IE I AT T ORA/E Y May 8, 1951 J. P. MITCHELL 2,551,892

PHOTOGRAPHIC FILM DEVELOPING AND FIXING APPARATUS Filed Aug. 2, 1948 2 Sheets-Sheet 2 4 Z3 /5 Z/ /7 Z6 Z3 /8 i JOHN P MITCHELL INVENTOR.

BY. I

/2 f7 5 a Z J ATTORNE/ Patented May 8, 195i PHOTOGRAPHIC FILM DEVELOPING AND FIXING APPARATUS John P. Mitchell, Dallas, Tex.

Application August 2, 1948, Serial No. 42,076

3 Claims.

This invention relates to new and useful improvements in photographic film developing and fixing apparatus, and is more particularly adapted for use for the developing of clinical X-ray film such as is used in medical and dental treatment.

Considerable difficulty has been experienced, in small clinics and medical and dental ofiices, in the developing of photographic film after exposure, inasmuch as proper developing of the film requires that the developing solution, the Wash water, and the fixer solution be maintained at substantially a constant normal temperature; and during hot weather the temperatures of the developer, fixer and Washing water may become too warm, or, during cold weather, the temperature of the solutions may become too cold. Various methods have been employed to reduce the temperatures of the developing solution, fixer solution and wash water during hot weather, and to raise the temperature in cold weather. One of the more common methods of lowering the temperature of the solution in hot weather is to place the developing tank and fixer tank in a tray of water containing ice or chemical solutions, or to surround the tray with Dry Ice, but this is very unsatisfactory inasmuch as the temperature constantly changes as the ice melts or upon addition of new ice to the tray, and therefore results in unsatisfactory film developing. Likewise, various means, such as electric lamps, chemical solutions and the like, have been employed for maintaining the developer, fixer and washing solutions at the desired temperature when the weather is cold, also with unsatisfactory results.

It is, therefore, one of the objects of this invention to provide a compact photographic film developing apparatus having means for maintaining the temperature of the developer solution, the fixer solution and the Washing water at any desired temperature range regardless of the surrounding atmospheric conditions.

A particular object of the invention is to provide an apparatus of the character described, wherein the developer solution and fixer solution are each contained in separate receptacles or tank trays removably mounted in a housing having a washing water tank therein, and wherein the developer and fixer solution receptacles are disposed in the washing Water tank in the housing and in contact with the washing Water in said tank, and means is provided in the tank for controlling the temperature of the washing water and thus controlling the temperatures of the fixing solution and developing solution; the washing water thus being used as a temperature control medium in the apparatus.

Another object of the invention is to provide, in an apparatus of the character described, an improved receptacle or tank tray for containing developer solution or fixer solution and having formed therein means for separating a plurality of racks for holding photographic film in position for developing or fixing in the solution.

A further object of the invention is to provide an improved film holding rack having guide means for protecting the film held by the rack and engaging in spaced grooves in the developer and fixer receptacles for spacing the racks apart to prevent damage to the film.

A still further object of the invention is to provide, in a film developing apparatus of the character described, means in the washing water tank of the apparatus for holding the developed and fixer film rack or' holder in place in the washing water.

Another object of the invention is to provide a developing apparatus of the character described which is compact in form, economical to manufacture and maintain and service, and which is suitable for use in small clinics or individual ofiices, and wherein the tanks and developing apparatus may be maintained constantly in condition for immediate use.

Additional objects and advantages of the invention will readily be apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

Figure 1 is an isometric view, partly in elevation and partly in section, showing a photographic developing and fixing apparatus constructed in accordance with the invention,

Figure 2 is a transverse vertical sectional view through the apparatus of Figure 1,

Figure 3 is a vertical sectional view taken on the line 33 of Figure 2, and

Figure 4 is a front elevation of a film holder rack constructed in accordance with the invention.

In the drawings, the numeral [6 designates a box-like container substantially rectangular in configuration and mounted on a base plate Ii, being spaced therefrom by legs i2 extending upwardly from the corners of the base plate. The container or housing [0 has a front wall 13, a rear wall I4, side walls l5, and a bottom IS. A top or cover I! is secured by hinges l8 to the upper end of the rear wall of the housing and is arranged to adjustably open and close the upper end of such housing. The walls and bottom of the housing, as well as the cover, may be made of any suitable material having the desired insulating and corrosion-resisting characteristics. For example, as illustrated, the con tainer may be formed of enamel covered sheet metal inner and outer shells spaced from each other and having a suitable insulating material, such as cork, glass wool or the like, therebetween, in the usual well-known manner. Or, if desired, the container may be formed of hard vulcanized rubber, Bakelite or any other suitable plastic material.

The interior of the container it! constitutes a large tank or chamber id for receiving wash water, as will hereinafter be described. Within the tank Zil are mounted a narrow deep rectan gular developing solution receptacle or tank tray 2i and a similar narrow deep fixer solution receptacle or tank tray 22. Each of the receptacles is provided with a laterally extending lug o-r ear 23 at the upper end of each of thei narrow end Walls, and these cars engage in recesses 2d provided in the upper ends of the front and back walls of the housing, said recesses being so spaced that the receptacles are positioned adjacent the side walls of the wash water tank 253, as clearly shown in Figures 1 and 2, with the tops of the n receptacles disposed below the upper open end of the tank. The receptacles 2i and 22 are preferably formed of a noncorrosive plastic material, such as Bakelite or hard vulcanized rubher, but may be formed of noncorrosive metal or glass, if desired. Vertically extending spaced grooves 25 are formed in the interior surface of the narrow end walls of the receptacles for bolding and guiding film holders, as will hereinafter be more fully explained. The receptacles are of such size that they are spaced from the front and rear walls of the container, and also are spaced from the side walls and bottom thereof, whereby wash water in the tank 20 may circulate exteriorly of all sides of the receptacles. If desired, lifting lugs 26 may be formed on each long side of the receptacles to facilitate handling of the receptacles by the user.

Inwardly projecting hanger or supporting ribs or platforms 2'! are provided near the upper end of the central portion of the interior of the front and rear walls of the container l0, and these platforms have vertically extending spaced grooves 28 formed therein for receiving a film holder and supporting the same in the wash water, as will hereinafter be explained.

A drain pipe 29, having a valve 29a. connected therein, extends through the bottom wall of the container ill and communicates with the interior of the tank 2t, whereby water in the tank may be drained through the pipe when desired. The valve will, of course, control the flow of water from the tank.

An electric heating coil 3!) is mounted inside the tank 29, and is positioned just above the bottom thereof for heating the water in the tank. The heating coil is preferably substantially rectangular in configuration and has electric leads 3! extending upwardly and outwardly through a resilient thermal sealing bushing removably mounted in a notch formed in the upper end of one of the side walls of the container and adapted to be connected to a suitable source of electric power (not shown), by means of which the coil is energized to heat the water when desired. A plurality of spaced coils of coolant conducting pipe 32 are mounted along the inne vertical walls of the tank 20 surrounding the receptacles 2! and 22, and the ends 33 of this coolant pipe extend upwardly and outwardly through a pair of resilient thermal sealing bushings removably mounted in notches formed in the upper end of one of the side walls of the container, and then extend downwardly and are connected with a refrigerator motor compressor unit 3i mounted below the container E9 on the base plate ll, whereby the coolant is circulated through the coolant pipe and cools the water in the tank. An electrical conductor 35 extends from the motor of the refrigerating unit to a suitable source of electricity for operating the same.

The operation of both the heating coil 39 and the coolant coil 32 of the apparatus are c0ntrolled by means of a thermostat dill, mounted on the container and having an electrical connection with the electric leads from the heating coil and from the motor of the refrigerating unit. The thermostat may be of any desired or suitable type having'a two-way switch therein or may consist of a pair of separate thermostatically controlled switch units, for causing the heating coil to be heated when the temperature of the water drops too low, or for causing the refrigerating unit to be operated if the temperature of the water rises too high. If separate thermostat controlled switch units are used, either may be cut off, if desired, to permit only the desired one of the heating or cooling units to operate.

Any desired suitable type of film holder or rack may be employed for positioning the photographic film in the receptacles or tank trays 2| and 22 and in the wash water in the tank 20, but the holder illustrated in Figure 4 is preferable. The holder includes a wire frame 45 formed in substantially a U-shape and having a bottom as and parallel upright arms ll. The upper end of each arm of the wire frame is bent outwardly and then bent upon inwardly itself to form a projecting shoulder 48 at the upper end of each side of the frame. The inner ends of the wires are then joined at the center to form a rigid structure. An elongate central bar d9 extends upwardly from the central portion of the bottom piece 46 of the frame to the center of the upper portion of the frame and is provided with a plurality of spaced spring clip members 5d of the customary type used for holdin photographic film. The clips 51] are so positioned on each side of the bar that the film gripped therein is held in the plane of the frame 45 and spaced from the side arms 4'! thereof. The size of the frame is such that the upright arms ll will engage in the grooves 25 in the developing and fixing solution receptacles and in the grooves 29 in the supporting platforms in the Wash water tank, and the shoulders 38 will engage upon the upper ends of the receptacles and the platforms to support the frame in position in such receptacles or on the platforms. Since the film is held spaced from the side arms M of the frame, it is believed manifest that the film will not wipe or rub against the end walls of the receptacles or of the water tank. Likewise, since the clips 5!] are disposed 'on each side of the upright bar 49 of the holder in such manner that the film lies in the plane of the frame, and since the grooves 25 in the receptacles and the grooves 25 in the platforms in the tanks are spaced apart, it will be seen that the film sections will not engage and rub against each other. Thus, the film is protected against damage during the. developing, fixing and washing operations.

' In use, the wash water tank 20 is filled with a suitable quantity of water, and the developer receptacle or tank tray 2| is filled with a developing solution to a desired depth and the receptacle is then lowered into the Water in the tank until the ears 23'are engaged in the recesses 24 on one side of the tank, as clearly shown in Figure 1. The fixer receptacle or tank tray 22 is filled with fixer solution in the desired amount and is likewise lowered into the Wash water tank until the ears 23 at the ends of the receptacle engage in the recesses 24 near the other side of the tank to support the receptacle in the tank. The space in the tank between the receptacles provides for access to the wash water for washing the film. A safety over-flow pipe 4| may be provided in the wash water tank for preventing the water therein from rising above'a predetermined level in the tank, said over-flow pipe connecting with the outlet pipe 29 for conducting the excess water to a suitable drain.

When the developer and fixer receptacles have been positioned in the wash water tank in the manner just described, and the heating coil and the refrigerator motor compressor unit have been connected to a suitable supply of electric power, if the temperature of the wash water is not at the proper or desired temperature range for which the thermostat is set, either the refrigerator mechanism or the heating unit will be put into operation to lower or raise the temperature of the Wash water to the desired range.

Since the wash water is in heat-exchanging contact with the exterior of the developer and fixer receptacles or tank trays, it will be seen that the liquids contained in such receptacles will be maintained at the same temperature as the Wash water. Thus the washing water is used as a temperature control medium for maintaining the temperatures of the fixer solution, the developer solution and the wash water at the desired range.

Since the container Ill and the cover I 1 are formed of an insulatin material, and since the thermostat 40 automatically controls the operation of the heating coil and the cooling unit, it will be seen that the temperature of the liquids in the container will be maintained at any desired temperature range regardless of the surrounding atmospheric conditions.

When the film on the holder 45 has been positioned in the developer receptacle 2| for a sufficient length of time to satisfactorily develop the film, the film is removed from such developer receptacle and washed in the wash water in the tank 20 between the receptacles and is then immersed in the fixer solution in the fixer receptacle 22. After the passage of a sufiicient time for properly fixing the developed film, the film holder 45 is lifted from the fixer receptacle and positioned on the platform 28 in the wash water tank and is permitted to remain immersed in the water in such tank until the film has been washed clean. During the time which the film is immersed in the various .solutions or water, the cover I! for the container may be closed to prevent light from acting upon the film. Also, when the container is closed, as aforesaid, the temperatures of the solutions and the water therein are maintained substantially constant at the desired normal range.

If desired, a suitable agitator or impeller (not shown) may be mounted in the water tank for agitating the water therein to insure an even distribution of temperature within the tank. Furthermore, the wash water may be changed as often as desired by drawing through the drain pipe '29 and refilling the tank.

While the heating and cooling coil units have been shown and described as removably mounted in the water tank, whereby they may be removed for repair or replacement, or for cleaning the tank, it will readily be seen that the electric lead from the heating coil and the ends of the cooling coils may be directed through lateral openings in the side wall of the tank, if desired. In such case the units would not be readily removable.

From the foregoing, it will be seen that an improved compact film developing and fixing apparatus has been provided which is suitable for use in small clinics and individual offices, and wherein the temperature of the solutions and the water in the apparatus is maintained at the desired operating range, whereby the apparatus is constantly in condition for immediate use. Furthermore, it will particularly be seen that an apparatus of the character described has been provided wherein the receptacles containing the developer solution and the fixer solution are removably mounted in the wash water tank, such receptacles being disposed in heat-exchanging contact with the wash water in the tank whereby the Wash water is utilized as a temperature control medium for controlling the temperatures of the fixer solution and the developer solution and the wash water simultaneously.

It will also be seen that an improved film holder has been provided, and means has been provided in each of the receptacles and in the wash water tank for supporting the film holder in proper position for protecting the film held in the holder against damage from rubbing against adjacent film or against the side walls of the receptacles or tank.

Further, the solutions and water in the apparatus are automatically maintained at the desired temperature level or range and the device is constantly ready for immediate use.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and. desire to secure by Letters Patent is:

l. A film developing apparatus including, an insulated wash water tank, a first receptacle adapted to contain a developing solution and removably positioned in the wash water tank, a second receptacle adapted to contain a fixing solution and removably positioned in the wash water tank and spaced from the first receptacle to provide access between the receptacles to the water in the wash water tank for washing film therein, means detachably secured to the walls of said tank between said receptacles for supporting photographic film in the wash water, and means in the wash water tank for controlling the temperature of the wash water, the water in the wash water tank contacting the side and bottom walls of the developer and fixer receptacle so as to be in heat exchanging relationship therewith, whereby the temperatures of the solutions in the developer and fixer receptacles are likewise controlled.

2. A film developing apparatus including, an insulated wash water tank, a first receptacle adapted to contain a developing solution and removably positioned in the wash water tank, means on the receptacle and the tank for supporting the receptacle in the tank below the upper end of the tank, a second receptacle adapted to contain a fixing solution and removably positioned in the wash water tank and spaced from the first receptacle to provide access between the receptacles to the water in the wash- Water tank for washing film therein, means on the receptacle and tank for supporting said second receptacle in the tank below the open upper end thereof, means removably positioned upon the walls of said tank between said receptacles for supporting photographic film in the wash water, and means in the wash water tank for controlling the temperature of the wash water, the water in the wash water tank contacting the sides and the bottom walls of the developer and the fixer receptacles so as to be in heat exchanging relationship therewith, whereby the temperatures of the solutions in the developer and fixer receptacles are likewise controlled.

3. A film developing apparatus including, an insulated wash water tank, a first tank tray adapted to contain a developing solution removably positioned in the tank, a second tank tray adapted to contain a fixing solution removably positioned in the wash water tank and spaced from the first tank tray, the space between the tank. trays providing for access to the water in the tank for washing photographic film, supporting members on the walls of the Wash water tank between the trays receiving racks rernovably positioned on said supporting members for sup- 8 porting photographic film in the wash water, and means in the wash water tank for controlling the temperature of the water therein, the water in the tank contacting the side and bottom walls of the tank trays so as to be in heat exchanging relationship therewith, whereby the temperature of the solutions in the developer and fixer tank trays is controlled and maintained substantially uniform with the temperature of the water in the tank.

JOHN P.- MITCHELL.

REFERENCES CITED The following references are of record in the file of this patent:

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